Plasma doping method and manufacturing method of semiconductor device

ABSTRACT

A plasma doping method capable of introducing impurities into an object to be processed uniformly is supplied. Plasma of a diborane gas containing boron, which is a p-type impurity, and an argon gas, which is a rare gas, is generated, and no bias potential is applied to a silicon substrate. Thereby, the boron radicals in the plasma are deposited on the surface of the silicon substrate. After that, the supply of the diborane gas is stopped, and bias potential is applied to the silicon substrate. Thereby, the argon ions in the plasma are radiated onto the surface of the silicon substrate. The radiated argon ions collide with the boron radicals, and thereby boron radicals are introduced into the silicon substrate. The introduced boron radicals are activated by thermal processing, and thereby a p-type impurity diffusion layer is formed in the silicon substrate.

TECHNICAL FIELD

The present invention relates to a plasma doping method for introducingimpurities into the inside of an object to be processed and amanufacturing method of semiconductor device including a formation stepof an extension region.

BACKGROUND ART

It is known that a short channel effect, in which a leakage currentflows at the time of an off-operation of a transistor, arises in anMISFET (Metal Insulator Silicon Field Effect Transistor), which is oneof semiconductor devices, when the gate length thereof is short, and itis known to form an extension region which is shallow than thesource/drain regions in order to suppress the short channel effect.

In the formation of such an extension region, it is required to form thedepth thereof to be more shallow (e.g. 10 nm or less) in associationwith the recent further miniaturization of the MISFET. The extensionregion is generally formed by introducing impurities into a substrate,and after that, by activating the introduced impurities by the thermalprocessing thereof. For the introduction of the impurities, an ionimplantation method of accelerating ions of impurities to inject theions into a substrate has conventionally been used. In order to form ashallow extension region by the use of the ion implantation method, itis necessary to make the acceleration energy of ions small. If the ionsof the impurities desired to be introduced are light, such as boronions, many accelerated ions have diffused before they reach thesubstrate when their acceleration energy is made to be small.Consequently, it was difficult to form a shallow extension region by theuse of the ion implantation method.

Accordingly, it is known to use a plasma doping method of introducingimpurities into a substrate by exposing the substrate to plasmacontaining the impurities therein that are desired to be introduced, andby applying bias potential to the substrate (see, for example, patentdocument 1).

In the plasma doping method described in the patent document 1, aphenomenon in which radicals in the plasma deposit on a surface of thesubstrate and a phenomenon in which ions accelerated by the biaspotential are radiated onto the substrate to be drawn into the substratesimultaneously occur. It is needed to deposit the radicals uniformly onthe surface of the substrate and to radiate the ions uniformly to thesubstrate here in order to introduce the impurities uniformly in thesubstrate by using the plasma doping method. That is, it is necessary toobtain a uniform in-plane distribution of the radicals and a uniformin-plane distribution of ions on the surface of the substrate.

In order to obtain the uniform in-plane distribution of the ions on thesurface of the substrate, it is possible to control the plasma by, forexample, a magnetic field. However, because the radicals and the ionsare different from each other in the existence of electric charges andthe like, and because the radicals exist more than the ions in theplasma, the plasma controlled in order to obtain the uniform in-planedistribution on the surface of the substrate does not enable theobtainment of the uniform in-plane distribution of the radicals on thesurface of the substrate, and does not enable the uniform deposition ofthe radicals on the surface of the substrate. As a result, the plasmadoping method described in the patent document 1 has a problem of theimpossibleness of the uniform introduction of impurities into thesubstrate because the method cannot simultaneously secure both of theuniform in-plane distributions of the radicals and the ions on thesurface of the substrate.

Moreover, the plasma doping method causes a disadvantage of the etchingof the surface of the substrate by the ions because the drawing speed ofthe ions is generally faster than the depositing speed of the radicalsin the processing apparatus executing the plasma doping method describedin the patent document 1. Consequently, if the plasma doping methoddescribed in the patent document 1 is applied to the formation of theextension region, the shallow extension region could be formed, but thesurface of the substrate is etched, and consequently the sheetresistance value of the extension region formed in the substrate ishigh.

PRIOR ART DOCUMENT Patent Document

-   Patent Document 1: JP-A-2004-128210

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

In view of the respects described above, a first problem of the presentinvention is to provide a plasma doping method capable of introducingimpurities uniformly into the inside of an object to be processed.Moreover, a second problem of the present invention is to provide aplasma doping method capable of preventing the object to be processedfrom being etched by the ions. Moreover, a third problem of the presentinvention is to provide a manufacturing method of a semiconductor devicehaving an extension region in which impurity concentration is uniform.Moreover, a fourth problem of the present invention is to provide amanufacturing method of a semiconductor device capable of forming a lowresistance extension region.

Means for Solving the Problems

In order to solve the first problem, a plasma doping method of thepresent invention is that of introducing impurities into an inside of anobject to be processed. The method comprises: a first step of generatingplasma of a gas containing the impurities to deposit radicals of theimpurities in the plasma on a surface of an object to be processed; anda second step of radiating ions to the radicals deposited on the surfaceof the object to be processed at the first step. In addition, the objectto be processed to which the impurities are introduced in the presentinvention includes not only a substrate but also a film.

According to the present invention, because the step of depositing theradicals of the impurities on the surface of the object to be processedand the step of radiating the ions on the surface of the object to beprocessed are separated from each other, the in-plane distribution ofthe radicals of the impurities deposited on the surface of the object tobe processed and the in-plane distribution of the ions radiated to thesurface of the object to be processed can independently be controlled.Therefore, the in-plane distribution of the radicals containing theimpurities on the surface of the object to be processed is improved atthe first step, and the ions are radiated to the radicals of theimpurities, the in-plane distribution of which has been improved.Thereby, the impurities can be introduced uniformly into the inside ofthe projecting object.

In the present invention, it is appropriate to set a time until theradicals deposited at the first step do not exist on the surface of theobject to be processed based on an etching rate of the radicals of theimpurities etched by the ions radiated at the second step, and toperform the second step for the set time. Hereby, the radiation of theions can be ended at the time point when the radicals of the impuritiesdo not exist on the surface of the object to be processed. Consequently,the etching of the surface of the object to be processed by the ions canbe prevented, and the rises of the sheet resistance value of the objectto be processed can be prevented.

In the present invention, if the first and the second steps are executedin a same processing chamber, it is appropriate to generate the plasmaof the gas containing the impurities and not to apply any bias potentialto a substrate at the first step, and it is appropriate to stop thesupply of the gas containing the impurities and to apply bias potentialto the substrate at the second step.

In order to solve the second problem, a plasma doping method of thepresent invention is that of generating plasma of a gas containingimpurities and of introducing radicals of the impurities in the plasmainto an inside of an object to be processed by means of ions whiledepositing the radicals on a surface of the object to be processed,wherein a depositing speed of the radicals to the surface of the objectto be processed and an etching speed of the radicals etched by the ionsare made to be equal to each other. In addition, the object to beprocessed into which the impurities are introduced is not only asubstrate but also a film.

In the present invention, the etching of the radicals indicates that theradicals are pushed in the inside of the projecting object by the ions,or that the radicals scatter from the surface of the object to beprocessed and thereby the radicals disappear from the surface of theobject to be processed. Moreover, in the present invention, that thedepositing speed of the radicals and the etching speed are equal to eachother does not indicate that both the speeds are physically the same,but indicates that the surface of the object to be processed is coveredby a layer of the radicals.

According to the present invention, because the surface of the object tobe processed is covered by the radicals of the impurities at the time ofintroducing the radicals of the impurities into the inside of the objectto be processed by making the depositing speed and the etching speed ofthe radicals of the impurities equal to each other, the surface of theobject to be processed can be prevented from being etched by the ions.Consequently, when the present invention is applied to the formation ofan extension region, the surface of the substrate can be prevented frombeing etched by the ions, and the sheet resistance value of theextension region formed in the substrate can be prevented from rising.

In the present invention, it is possible to control the dose quantity ofthe impurities introduced in the inside of the object to be processed byadjusting an integrated deposition quantity of the radicals deposited onthe surface of the object to be processed.

In the present invention, it is possible to control a distribution ofthe impurities in a depth direction, the impurities being introducedinto the inside of the object to be processed, by adjusting radiationenergy of the ions. In addition, the distribution of the impurities in adepth direction indicates the concentration distribution of theimpurities along the depth direction of an object to be processed in thepresent invention.

In the present invention, the ions may be radiated to the surface of theobject to be processed before the radicals are deposited on the surfaceof the object to be processed. Hereby, the impurities introduced intothe inside of the object to be processed can be prevented from beingexcessively diffused by a thermal processing of a post-process.

In order to solve the third problem, a manufacturing method of asemiconductor device of the present invention, comprises: a step offorming a gate insulation film on a surface of a substrate; a step offorming a gate electrode on the gate insulation film; a step of formingan extension region with the gate electrode used as a mask; a step offorming a spacer covering a side wall of the gate electrode; and a stepof forming source/drain regions by using the gate electrode and thespacer as masks. The step of forming the extension region includes: afirst step of generating plasma containing impurities to depositradicals of the impurities in the plasma on the surface of thesubstrate; and a second step of radiating ions to the radicals depositedon the surface of the substrate at the first step.

According to the present invention, because the step of depositing theradicals of the impurities on the surface of the substrate and the stepof radiating the ions on the surface of the substrate are separated fromeach other at the time of forming the extension region, the in-planedistribution of the radicals of the impurities deposited on the surfaceof the substrate and the in-plane distribution of the ions radiated tothe surface of the substrate can independently be controlled. Therefore,the in-plane distribution of the radicals of the impurities on thesurface of the substrate is improved at the first step, and the ions areradiated to the radicals of the impurities, the in-plane distribution ofwhich has been improved, at the second step. Thereby, the impurities canbe introduced uniformly in the inside of the substrate.

In the present invention, the step of forming the gate electrodeincludes a step of forming a gate electrode film to become the gateelectrode, a step of introducing the impurities into the gate electrodefilm, and a step of patterning the gate electrode film in which theimpurities are introduced, wherein the step of introducing theimpurities into the gate electrode film includes a first sub-step ofgenerating the plasma of the gas containing the impurities to depositthe radicals in the plasma on a surface of the gate electrode film, anda second sub-step of radiating the ions to the radicals deposited on thesurface of the gate electrode film at the first sub-step.

Hereby, the in-plane distribution of the radicals of the impuritiesdeposited on the surface of the gate electrode film and the in-planedistribution of the ions radiated onto the surface of the gate electrodefilm can independently be controlled at the time of introducing theimpurities into the gat electrode film. Consequently, the in-planedistribution of the radicals of the impurities on the surface of thegate electrode film is improved at the first sub-step, and the ions areradiated to the radicals of the impurities, the in-plane distribution ofwhich has been improved, at the second sub-step. Thereby, the impuritiescan be introduced uniformly in the gate electrode film.

In order to solve the fourth problem, a manufacturing method of asemiconductor device of the present invention, comprises: a step offorming a gate insulation film on a surface of a substrate; a step offorming a gate electrode on the gate insulation film; a step of formingan extension region by using the gate electrode as a mask, a step offorming a spacer covering a side wall of the gate electrode; and a stepof forming source/drain regions with the gate electrode and the spacerused as masks. The step of forming the extension region is that ofgenerating plasma of a gas containing impurities to introduce radicalsof the impurities in the plasma into an inside of the substrate by meansof ions while depositing the radicals on the surface of the substrate,and a depositing speed of the radicals on the surface of the substrateand an etching speed of the radicals etched by the ions are made to beequal to each other.

According to the present invention, because the surface of the substrateis covered by the radicals of the impurities at the time of forming theextension region by making the depositing speed and the etching speed ofthe radicals of the impurities equal to each other, the surface of thesubstrate can be prevented from being etched by the ions, andconsequently a low resistance extension region can be formed.

In the present invention, the step of forming the gate electrodeincludes: a sub-step of forming a gate electrode film to become the gateelectrode; a sub-step of introducing the impurities into the gateelectrode film; and a sub-step of patterning the gate electrode film inwhich the impurities are introduced. The sub-step of introducing theimpurities into the gate electrode film is that of generating the plasmaof a gas containing the impurities to introduce the radicals of theimpurities in the plasma into an inside of the gate electrode film bymeans of the ions while depositing the radicals on a surface of the gateelectrode film, and a depositing speed of the radicals on the surface ofthe gate electrode film and an etching speed of the radicals etched bythe ions are made to be equal to each other.

Hereby, because the surface of the gate electrode film is covered by theradicals of the impurities at the time of introducing the impuritiesinto the gate electrode film by making the depositing speed and theetching speed of the radicals of the impurities equal to each other, thesurface of the gate electrode film can be prevented from being etched bythe ions. Consequently, the rise of the sheet resistance value of thegate electrode film can be prevented.

In addition, in the present invention, the ions of a rare gas can beused as the ions mentioned above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view for describing the configuration of a plasma dopingapparatus used in a first embodiment of the present invention.

FIGS. 2(A) to 2(C) are views for describing a plasma doping method ofthe first embodiment of the present invention.

FIG. 3 is a diagram showing a relation between a deposition time and adeposition film thickness of boron radicals.

FIG. 4 is a diagram showing SIMS analysis results of the cases of usingthe plasma doping method of the first embodiment of the presentinvention and a plasma doping method of prior art.

FIG. 5 is a diagram for describing changes of a sheet resistance valueto argon ion radiation time.

FIGS. 6(A) to 6(C) are views for describing a manufacturing method of anMISFET of a second embodiment of the present invention.

FIGS. 7(A) to 7(D) are views for describing the manufacturing method ofthe MISFET of the second embodiment of the present invention.

FIGS. 8(A) to 8(C) are views for describing the manufacturing method ofthe MISFET of the second embodiment of the present invention.

FIGS. 9(A) and 9(B) are views for describing a plasma doping method of athird embodiment of the present invention.

FIGS. 10(A) and 10(B) are views for describing the manufacturing methodof an MISFET of a fourth embodiment of the present invention.

FIGS. 11(A) to 11(C) are views for describing the manufacturing methodof the MISFET of the fourth embodiment of the present invention.

FIGS. 12(A) to 12(C) are views for describing the manufacturing methodof the MISFET of the fourth embodiment of the present invention.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

In the following, a plasma doping method of a first embodiment of thepresent invention will be described with reference to the accompanyingdrawings. In addition, the elements common to in each drawing aredenoted by the same marks, and duplicating descriptions are omitted.

A processing apparatus used in the present embodiment is, for example,an ICP (inductively coupled plasma) type plasma doping apparatus asshown in FIG. 1, and is equipped with a vacuum chamber 1 capable offorming a vacuum atmosphere.

The upper part of the vacuum chamber 1 is configured in cylinder portion2, made of a dielectric, such as quartz, and the cylinder portion 2functions as a plasma generation unit. Three ring-shaped magnetic fieldcoils 3, 4, and 5, which can form a magnetic neutral line (NLD) in thecylinder portion 2, are arranged on the outside of the cylinder portion2. A looped antenna coil 6 is arranged between the cylinder portion 2and the magnetic field coils 3-5. The antenna coil 6 is connected to ahigh-frequency power source 8 through a capacitor 7 to be configured tobe able to apply high-frequency power (also called “antenna RF power”)for plasma generation.

An upper part aperture of the cylinder portion 2 is covered by a topplate 9, in which a gas inlet 10 for introducing a gas into the vacuumchamber 1 is formed. The other end of the gas inlet 10 communicates witha gas source through a not-shown gas tube and a not-shown mass flowcontroller.

Moreover, an electrode 12 is arranged at the bottom of the vacuumchamber 1 with an insulator member 11 put between the electrode 12 andthe bottom. A substrate 13 is placed on the top surface, which is asubstrate placing surface, of the electrode 12. A high-frequency powersource 15 is connected to the electrode 12 through a blocking capacitor14, so that bias potential can be applied. An exhaust pipe 16 isconnected to the wall surface of the vacuum chamber 1 on the outside ofthe electrode 12. The exhaust pipe 16 communicates with vacuum exhaustmeans, composed of a not-shown turbo molecular pump, a not-shown rotarypump, a not-shown conductance-variable valve, or the like.

When a gas is supplied into the vacuum chamber 1 through the gas inlet10 and currents are made to flow through the upper and the lowermagnetic field coils 3 and 5 in the same direction and further a currentis made to flow through the intermediate magnetic field coil 4 into thereverse direction, then a ring-like magnetic neutral line 16 is formedin the vacuum cylinder portion 2. When high-frequency power is suppliedto the antenna coil 6 in this state, plasma is generated along themagnetic neutral line 16.

Here, because the extent of the magnetic neutral line 16 in thehorizontal direction changes by the suitable adjustment of the currentvalues of the currents made to flow through the magnetic field coils 3and 5 and the current value of the current made to flow through theintermediate magnetic field coil 4, the extent distribution of theplasma can be controlled.

Next, a plasma doping method using the aforesaid plasma doping apparatusis described by exemplifying the introduction of boron into the siliconsubstrate 13 with reference to FIG. 2.

After the silicon substrate 13 is placed on the electrode 12, the vacuumexhaust means is operated to perform the vacuuming of the vacuum chamber1 up to a desired degree of vacuum.

Next, a diborane (B₂H₆) gas, containing boron (B), which is a p-typeimpurity, Argon (Ar) gas, which is a rare gas, are supplied into thevacuum chamber 1 through the gas inlet 10. At the same time, currentsare made to flow through the upper and the lower magnetic field coils 3and 5 into the same direction, and a current is made to flow through theintermediate magnetic field coil 4 into the reverse direction, andthereby the magnetic neutral line 16 is formed in the cylinder portion2. Furthermore, high-frequency power is applied from the high-frequencypower source 8 to the antenna coil 6, and thereby plasma is generatedalong the magnetic neutral line 16.

Because no negative bias potential is applied to the electrode 12, theions (Ar⁺, B_(x)H_(y) ⁺) in the plasma is not drawn into the siliconsubstrate 13. Consequently, as shown in FIG. 2(A), the deposition ofboron radicals 21 onto the surface of the silicon substrate 13 isdominant.

Here, in order to improve the in-plane distribution of the boronradicals 21 deposited on the surface of the silicon substrate 13, it isneeded to improve the distribution of the boron radicals 21 in theplasma.

Accordingly, in the present embodiment, the distribution of the boronradicals 21 in the plasma is controlled by changing the extant of themagnetic neutral line 16 by adjusting the value of the current flowingthrough the magnetic field coils 3 ⁻⁵. For example, the in-planedistribution of the boron radicals 21 depositing on the surface of thesilicon substrate 13 can be controlled by using the following depositionconditions.

[Deposition Conditions]

Flow rate of B₂H₆ diluted by 10% He: 6.14 [sccm]

Flow rate of Ar: 38.85 [sccm]

Concentration of B₂H₆: 1.36[%]

Process pressure: 0.1 [Pa]

Antenna RF power: 300 [W]

Bias RF power: 0 [W]

Magnetic field coil currents (upper & lower/intermediate): 9.4 [A]/7.3[A]

After performing the deposition of the boron radicals 21 onto thesurface of the silicon substrate 13 for a predetermined time (forexample, 20 seconds to 40 seconds) under the aforesaid depositionconditions, the supply of the diborane gas is stopped, bias potential isapplied from the high-frequency power source 15 to the electrode 12while the supply of the argon gas and the application of thehigh-frequency power to the antenna coil 6 are continued. Hereby, asshown in FIG. 2(B), argon ions (Art) 22 are drawn (pulled) into thesilicon substrate 13. The argon ions 22 drawn into the silicon substrate13 collide with the boron radicals 21, and thereby the boron radicals 21are pushed into the silicon substrate 13.

At this time, as shown in FIG. 2(B), a part of the boron radicals 21 aare etched by the argon ions 22 to be scattered.

Here, in order to improve the in-plane distribution of the boronradicals 21 pushed in the silicon substrate 13, it is necessary toimprove the in-plane distribution of the argon ions 22 drawn into thesilicon substrate 13.

Accordingly, in the present embodiment, the distribution of the argonions 22 in the plasma are controlled by changing the extent of themagnetic neutral line 16 by adjusting the current values of the currentsflowing through the magnetic field coils 3-5. The distribution of theargon ions 22 in the plasma is different from that of the boron radicals21. For example, the in-plane distribution of the argon ions 22 drawninto the silicon substrate 13 can be controlled by using the followingargon ion radiation conditions. By changing the current value of theintermediate magnetic field coil 4 from the one in the aforesaiddeposition conditions, the extent of the magnetic neutral line 16 iscontrolled to the optimum one for obtaining the uniform in-planedistribution of the argon ions 22 on the surface of the siliconsubstrate 13.

[Argon Ion Radiation Conditions]

Flow rate of B₂H₆ diluted by 10% He: 0 [sccm]

Flow rate of Ar: 38.85 [sccm]

Process pressure: 0.1 [Pa]

Antenna RF power: 300 [W]

Bias RF power: 530 [W]

Bias vpp: 1.5 [V]

Magnetic field coil currents (upper & lower/intermediate): 9.4 [A]/7.6[A]

In addition, the bias RF power in the aforesaid argon ion radiationconditions may be set to 30 [W]. In this case, a bias peak-to-peakvoltage Vp is 0.2 [V], and the radiation energy of the argon ionsbecomes small.

After that, thermal processing is performed in a not-shown publiclyknown lamp annealing apparatus, and thereby the boron radicals 21introduced in the silicon substrate 13 are activated. As a result, asshown in FIG. 2(C), a p-type impurity diffusion layer 23 is formed inthe silicon substrate 13 to be in the depth of, for example, 10 nm orless, preferably 5 nm or less.

In the first embodiment described above, after depositing the boronradicals 21 on the surface of the silicon substrate 13, the argon ions22 are radiated onto the deposited boron radicals 21. The radiated argonions 22 collide with the boron radicals 21, and thereby the boronradicals 21 are pushed into the silicon substrate 13.

According to the present embodiment, because the deposition step of theboron radicals 21 onto the surface of the silicon substrate 13 and theradiation step of the argon ions 22 to the surface of the siliconsubstrate 13 are separated unlike the prior art plasma doping method,the in-plane distribution of the boron radicals 21 and the in-planedistribution of the argon ions 22 on the surface of the siliconsubstrate 13 can independently be adjusted by adjusting the currentvalues that are made to flow through the magnetic field coils 3 ⁻⁵ ateach step. Hereby, because the in-plane distribution of the boronradicals 21 on the surface of the silicon substrate 13 can be improved,the impurities can uniformly be introduced into the silicon substrate13.

Now, after depositing the boron radicals 21 on the surface of thesilicon substrate 13, the deposition film thickness of the boronradicals 21 can be measured by observing the silicon substrate 13 with across-sectional SEM. Here, it was found that a proportional relationexisted between the deposition time and the deposition film thickness asshown in FIG. 3 by the measurement of the deposition film thickness ofthe boron radicals 21 at the time of performing deposition of the boronradicals 21 by changing the processing time (hereinafter referred to as“deposition time”) in the aforesaid deposition conditions. Accordingly,the deposition film thickness can be controlled by adjusting thedeposition time. In addition, when the depositing speed (depositionrate) of the boron radicals under the aforesaid deposition conditionswas calculated, it was about 0.8 nm/min.

Now, in a plasma doping method of one step, as representative parametersfor determining a dose quantity (doping quantity), the concentration ofa gas containing impurities, a plasma density, bias potential, aprocessing time, and the like can be given. However, because theseparameters are not independent but have mutual interactions, the dosequantity has actually been measured to the respective conditions settingthese parameters.

In the present embodiment, as a result of changing the deposition filmthickness of the boron radicals 21 on the surface of the siliconsubstrate 13, radiating the argon ions 22 under the same conditions,respectively, and measuring the dose quantity of the impurities in thesilicon substrate 13, respectively, it was found that there was acorrelation between the deposition film thickness and the dose quantityof the boron radicals 21. From this result, it was found that the boronatoms taken into the silicon substrate 13 were not the ions (B_(x)H_(y)⁺) in the plasma injected by being accelerated by the bias potential,but were the boron radicals 21 deposited on the surface of the siliconsubstrate 13 and pushed in by the argon ions 22. Accordingly, the dosequantity of the impurities in the silicon substrate 13 can be controlledby adjusting the deposition film thickness (i.e., deposition time) ofthe boron radicals 21.

Moreover, the argon ions 22 were radiated while the radiation energy waschanged by changing the bias voltage with the deposition film thicknessof the boron radicals 21 fixed, and the distribution of the impuritiesin the depth direction at that time was measured. Consequently, it wasfound that there was a correlation between the bias voltage and thedistribution of the impurities in the depth direction. That is, it wasfound that the higher the bias voltage was, the deeper the positionwhere the impurities were distributed became. Accordingly, thedistribution of the impurities in the depth direction of the siliconsubstrate 13 can be controlled by adjusting the radiation energy (i.e.bias voltage) of the argon ions 22.

Consequently, according to the present embodiment, because the controlof the dose quantity of the impurities and the control of thedistribution of the impurities in the depth direction can separately andindependently be performed, it becomes easy to perform the conditionsetting at the time of applying the present embodiment to amanufacturing process of a semiconductor device.

Moreover, as the analysis results of a SIMS (Secondary Ion-microprobeMass Spectrometer) shown in FIG. 4, impurities were introduced insilicon substrates so as to be equal dose quantities and depthdistributions by using the plasma doping method of the presentembodiment and a one-step plasma doping method, respectively. Here, inthe plasma doping method of the present embodiment, after boron radicalswere deposited for 40 seconds under the aforesaid deposition conditions,argon ions were radiated for 5 seconds under the aforesaid argon ionradiation conditions. On the other hand, in the one-step plasma dopingmethod, the deposition of the boron radicals and the pushing-in of theboron radicals by the argon ions were simultaneously performed for 40seconds. The sheet resistance values of the silicon substrates in whichthe impurities were introduced were severally measured. The results werethat the sheet resistance value of the silicon substrate when theimpurities were introduced by the plasma doping method of the presentembodiment was 116[Ω/]. On the other hand, the sheet resistance value ofthe silicon substrate when the impurities were introduced by theone-step plasma doping method was 231[Ω/]. Consequently, it was foundthat the sheet resistance value lowered by pushing the boron radicalsinto the silicon substrate by argon ions. Accordingly, the rise of thesheet resistance value of the silicon substrate can be suppressed morethan that of the case of using the one-step plasma doping method byintroducing the impurities into the silicon substrate by using theplasma doping method of the present embodiment.

Moreover, it was found that the in-plane distribution of the sheetresistance values of the silicon substrates could be controlled within1% by controlling the in-plane distribution of the deposition filmthickness of the boron radicals on the surface of the silicon substrateto be within 3% by the standard deviation σ/average value.

Now, by introducing the impurities by two steps as described above, thesheet resistance value of the silicon substrate can be made to be lowerthan that of the case of introducing the impurities by one step.However, as shown by a solid line in FIG. 5, it was found that the sheetresistance value, which had once been lowered, rose as the argon ionradiation time became longer, and then became higher than the sheetresistance value R2 shown by a broken line in FIG. 5 in the case ofintroducing the impurities by the one-step plasma doping method (priorart).

As a result of an examination by the inventor of the present invention,it was found that the sheet resistance value R1 became lowest when noboron radicals existed on the surface of the silicon substrate (t1) bythe introduction of the boron radicals and the etching by the argonions, and that, if argon ions were continuously radiated after that, thesurface of the silicon substrate was etched by the argon ions (that is,the silicon atoms in which the boron atoms were introduced were etched),so that the sheet resistance value rose.

Accordingly, the decreasing speed (hereinafter referred to as “etchingrate”) of the boron radicals by the argon ions is obtained in advance,and a time until the boron radicals do not exist on the surface of thesilicon substrate is set on the basis of the etching rate to radiate theargon ions for the set time. Thereby, the surface of the siliconsubstrate can be prevented from being etched, and the rise of the sheetresistance value of the silicon substrate can be suppressed. Here, theetching rate of the boron radicals can be obtained from the observationresults obtained by depositing boron radicals on the surfaces of siliconsubstrates to be the same film thicknesses, radiating argon ions to theboron radicals for different radiation times, and observing therespective remaining film thicknesses of the boron radicals at that timewith a cross-sectional SEM.

As the aforesaid first embodiment, the plasma of a diborane gas and anargon gas are generated and no bias potential is applied to the siliconsubstrate 13 at the time of depositing the boron radicals 21, and thesupply of the diborane gas is stopped and bias potential is applied tothe silicon substrate 13 at the time of radiating the argon ions 22.Thereby, the deposition step of the boron radicals 21 and the radiationstep of the argon ions 22 can execute the same vacuum chamber 1. Hereby,throughput can considerably be improved in comparison with the case ofperforming both the steps in separate chambers.

Next, with reference to FIGS. 6-8, a manufacturing method of asemiconductor device of a second embodiment, to which the aforesaidplasma doping method of the first embodiment is applied, will bedescribed by illustrating a manufacturing method of a MISFET.

First, as shown in FIG. 6(A), a gate insulation film 32 is formed on asilicon substrate 31. As the gate insulation film 32, for example, notonly a silicon oxide film and a silicon oxynitride film, both having afilm thickness of from 0.5 nm to 1 nm, but also a high dielectricconstant film (high-k film), such as a HfO_(x) film, a HfSiO_(x) film,and a HfAlO_(x) film, all having a film thickness of from 2 nm to 3 nm,can be used. Also, a laminated film of the above-mentioned films can beused as the gate insulation film 32.

In addition, the silicon oxide film can be formed by using a thermaloxidization method, and the high dielectric constant film can be formedby using an ALD (atomic layer deposition) method and an MOCVD (metalorganic chemical vapor deposition) method.

Next, a polysilicon film having a film thickness of from 70 nm to 100 nmis formed on the gate insulation film 32 by a LPCVD (low pressurechemical vapor deposition) method as a gate electrode film 33 to be agate electrode 33 a. In addition, the materials of the gate electrodefilm 33 are not limited to the polysilicon, but silicon germanium, apublicly known metal, and the like can be used.

Next, impurities are introduced in the polysilicon film 33 by using theplasma doping method of the aforesaid first embodiment.

First, as shown in FIG. 6(B), the boron radicals 21 are deposited on thesurface of the polysilicon film 33. At this time, the aforesaiddeposition conditions can be applied, and it is appropriate to adjustthe deposition quantity (deposition time) of the boron radicals 21according to a target dose quantity of boron (for example, 5×10¹⁵[cm⁻²]).

After that, as shown in FIG. 6(C), the argon ions 22 are radiated, andthe boron radicals 21 deposited on the surface of the polysilicon film33 are pushed in. At this time, the aforesaid argon ion radiationconditions can be applied, and it is appropriate to adjust the radiationenergy of the argon ions 22 according to the target depth distributionof boron (for example, 1×10¹⁷ [cm⁻³] or less at 50 nm to 60 nm). Thatis, it is appropriate to adjust the radiation energy of the argon ions22 lest the impurities introduced in the polysilicon film 33 shouldreach the gate insulation film 32.

Then, a not-shown resist pattern is formed on the polysilicon film 33 byusing a lithography technique, and the polysilicon film 33 and the gateinsulation film 32 are etched with the resist pattern as a mask.Furthermore, for example, after the resist pattern has been removed bysuitably performing ashing processing and SPM (sulfuric hydrogenperoxide mixture) processing, thermal processing for activating theboron introduced in the polysilicon film 33 is performed in the publiclyknown lamp annealing apparatus. Hereby, as shown in FIG. 7(A), astructure in which the gate insulation film 32 and the gate electrode 33a, composed of a polysilicon film in which boron is introduced, arelaminated is formed.

Next, an extension region is formed in the silicon substrate 31 by usingthe plasma doping method of the aforesaid first embodiment.

First, as shown in FIG. 7(B), the boron radicals 21 are deposited on thesurface of the silicon substrate 31. At this time, the aforesaiddeposition conditions can be applied, and it is appropriate to adjustthe deposition quantity (deposition time) of the boron radicals 21according to the target dose quantity (for example, 1×10¹⁵ [cm⁻²]) ofboron.

After that, as shown in FIG. 7(C), the argon ions 22 are radiated topush in the boron radicals 21 deposited on the surface of the siliconsubstrate 31. At this time, the aforesaid argon ion radiation conditionscan be applied, and it is appropriate to adjust the radiation energy ofthe argon ions 22 according to the target depth distribution of boron(for example, 5×10¹⁸ [cm⁻³] or less at 10-15 nm).

Then, thermal processing for activating the boron introduced in thesilicon substrate 31 is performed in the publicly known lamp annealingapparatus. Hereby, as shown in FIG. 7(D), a p-type extension region 34having a depth of 10 nm or less is formed in such a manner that the gateelectrode 33 a lies between the extension regions 34.

Next, after forming a silicon oxide film on the whole surface of thesilicon substrate 31, the silicon oxide film is etched, and thereby, asshown in FIG. 8(A), a spacer 35 covering the side wall of the gateelectrode 33 a is formed by a self-aligned manner.

Then, as shown in FIG. 8(B), boron ions 36 are injected into the siliconsubstrate 31 with the gate electrode 33 a and the spacer 35 used asmasks by the ion implantation method. Furthermore, by activating theinjected boron ions 36 by thermal processing, source/drain regions 37deeper than the extension region 34 are formed as shown in FIG. 8(C). AMISFET can be obtained through the aforesaid steps.

In the second embodiment described above, after depositing the boronradicals 21 on the surface of the silicon substrate 31, the argon ions22 are radiated to the deposited boron radicals 21, at the time offorming the extension region 34 after the formation of the gateelectrode 33 a. The radiated argon ions 22 collide with the boronradicals 21, and thereby the boron radicals 21 are pushed into thesilicon substrate 31.

According to the present embodiment, the deposition step of the boronradicals 21 on the surface of the silicon substrate 31, and theradiation step of the argon ions 22 to the surface of the siliconsubstrate 31 are separated from each other, the in-plane distribution ofthe boron radicals 21 and the in-plane distribution of the argon ions 22on the surface of the silicon substrate 31 can independently becontrolled. Consequently, the in-plane distribution of the boronradicals 21 on the surface of the silicon substrate 31 is improved, andrare gas ions are radiated to the boron radicals 21 whose in-planedistribution has been improved. Thereby, the impurities can uniformly beintroduced into the silicon substrate 31, and the extension region 34 inwhich impurity concentration is uniform can be formed. Furthermore,according to the present embodiment, the rise of the sheet resistancevalue of the extension region 34 can be suppressed more than the case offorming the extension region by using the one-step plasma doping method.

Furthermore, in the present embodiment, it is possible to introduceboron into the polysilicon film 33 while suppressing the rise of thesheet resistance value of the polysilicon film 33, which is a gateelectrode film, similarly to the case of the aforesaid extension region34. Next, a plasma doping method of a third embodiment of the presentinvention will be described with reference to FIG. 9 by illustrating thecase of introducing boron into the silicon substrate 13. Because theplasma doping apparatus carrying out plasma doping processing is similarto that of the aforesaid first embodiment, the detailed descriptionthereof is omitted here.

Similarly to the first embodiment, after placing the silicon substrate13 on the electrode 12, the vacuum exhaust means is operated to performthe vacuuming of the vacuum chamber 1 to a desired degree of vacuum.

Next, a diborane (B₂H₆) gas containing boron (B), which is a p-typeimpurity, and an argon (Ar) gas, which is a rare gas, are supplied fromthe gas inlet 10 into the vacuum chamber 1. At the same time, currentsare made to flow through the upper and lower magnetic field coils 3 and5 in the same direction, and a current is made to flow through theintermediate magnetic field coil 4 in the reverse direction. Thereby,the magnetic neutral line 16 is formed in the cylinder portion 2.Furthermore, when high-frequency power is applied from thehigh-frequency power source 8 to the antenna coil 6, plasma is generatedalong the magnetic neutral line 16, and the boron radicals 21 in theplasma are deposited on the surface of the silicon substrate 13 as shownin FIG. 9(A). At this time, when high-frequency power (hereinafter alsoreferred to “bias RF power”) is applied from the high-frequency powersource 15 to the electrode 12, negative bias potential is applied to theelectrode 12, and the argon ions (Ar⁺) 22 in the plasma are drawn intothe silicon substrate 13.

When the argon ions 22 drawn into the silicon substrate 13 collide withthe boron radicals 21 deposited on the surface of the silicon substrate13, the boron radicals 21 are pushed into the silicon substrate 13, anda part of the boron radicals 21 a is scattered, as shown in FIG. 9(A).Consequently, the deposition of the boron radicals 21 on the surface ofthe silicon substrate 13 and the etching of the boron radicals 21 by theargon ions 22 simultaneously proceed.

Here, the etching speed of the boron radicals 21 by the argon ions 22generally easily becomes higher than the depositing speed of the boronradicals 21 on the surface of the silicon substrate 13. When the etchingspeed is higher than the depositing speed, the boron radicals 21deposited on the surface of the silicon substrate 13 are not only etchedby the argon ions 22, but also the surface of the silicon substrate 13,which is exposed by the etching of the boron radicals 21, is etched bythe argon ions 22. Because boron is entered into the etched siliconatoms, the sheet resistance value of the silicon substrate 13 rises.

In the present embodiment, in order to prevent the surface of thesilicon substrate 13 from being etched at the time of introducing theboron radicals 21 into the silicon substrate 13, the depositing speed ofthe boron radicals 21 on the surface of the silicon substrate 13 and theetching speed of the boron radicals 21 by the argon ions 22 are made toequal to each other. That is, the surface of the silicon substrate 13,into which the argon ions 22 are drawn at the time of introducing theboron radicals 21 into the silicon substrate 13, is made to be coveredby the boron radicals 21.

Because the deposition speed of the boron radicals 21 has a correlationwith the plasma density, the deposition speed can be controlled bysuitably adjusting at least one of the density and the flow rate of adiborane gas, the flow rate of an argon gas, a process pressure, andantenna RF power. On the other hand, because the etching speed has acorrelation with the radiation energy of the argon ions 22, the etchingspeed can be controlled by adjusting the bias RF power.

For example, the depositing speed of the boron radicals 21 and theetching speed of the boron radicals 21 by the argon ions 22 can be madeto be equal to each other by using the doping conditions described inthe following.

[Doping Conditions]

Flow rate of B₂H₆: 0.5 [sccm]

Flow rate of Ar: 49.5 [sccm]

Concentration of B₂H₆: 1.0[%]

Antenna RF power: 300 [W]

Bias RF power: 30 [W]

Magnetic field coil currents (upper & lower/intermediate): 9.4 [A]/7.3[A]

Here, the depositing speed of the boron radicals 21 can be obtained bydepositing the boron radicals 21 on the surface of the silicon substrate13 by not-performing the drawing of the argon ions 22 into the siliconsubstrate 13 by making the bias RF power zero, and by observing thesilicon substrate 13 with the cross-sectional SEM to obtain thedeposition film thickness of the boron radicals 21 obtained from theobservation result. As shown in FIG. 3, there is a proportional relationbetween the deposition time and the deposition film thickness of theboron radicals 21.

On the other hand, the etching speed of the boron radicals 21 can beobtained by performing doping processing by supplying the bias RF powerto the silicon substrate 13, on which the boron radicals 21 have beendeposited to a predetermined film thickness in advance, and by observingthe silicon substrate 13 with a cross-sectional SEM to obtain theetching speed from the film thickness of the boron radicals 21 obtainedby the observation result. In addition, because also the deposition ofthe boron radicals 21 proceeds while the doping processing, it isappropriate to consider an already-known depositing speed of the boronradicals at the time of obtaining the etching speed of the boronradicals 21.

After performing the introduction of the boron radicals 21 into thesilicon substrate 13 by using the aforesaid doping conditions for apredetermined time (for example, 20 seconds to 40 seconds), the supplyof the diborane gas and the argon gas is stopped, and the application ofthe antenna RF power and the bias RF power is stopped.

After that, thermal processing is performed in a not-shown publiclyknown lamp annealing apparatus, and thereby the boron radicals 21introduced in the silicon substrate 13 are activated. As a result, asshown in FIG. 9(B), the p-type impurity diffusion layer 23 is formed inthe silicon substrate 13 to a depth of, for example, 10 nm or less,preferably 5 nm or less.

In the third embodiment described above, while depositing the boronradicals 21 on the surface of the silicon substrate 13, the argon ions22 drawn into the surface of the silicon substrate 13 are made tocollide with the deposited boron radicals 21. Hereby, the boron radicals21 deposited on the surface of the silicon substrate 13 are pushed intothe silicon substrate 13, and a part of the boron radicals 21 isscattered from the surface of the silicon substrate 13.

According to the present embodiment, the depositing speed of the boronradicals 21 on the surface of the silicon substrate 13 and the etchingspeed of the boron radicals 21 by the argon ions 22 are made to be equalto each other, and thereby the surface of the silicon substrate 13 iscovered by the boron radicals 21 at the time of introducing the boronradicals 21 into the silicon substrate 13. Consequently, the surface ofthe silicon substrate 13 can be prevented from being etched by the argonions 22. Consequently, the low resistance p-type impurity diffusionlayer 23 can be formed.

For example, the sheet resistance value is 231Ω/ under the condition ofthe bias RF power being 530 W, at which value the etching speed becomeslarger than the depositing speed (the conditions other than the bias RFpower can be similar to those of the aforesaid doping conditions). Onthe other hand, the sheet resistance value is 205Ω/ under the aforesaiddoping conditions of the bias RF power being 30 W under which theetching speed and the depositing speed are equal to each other.

Because the depositing speed of the boron radicals 21 is obtained inadvance as described above, the integrated deposition film thickness ofthe boron radicals 21 can be changed by adjusting the doping processingtime. As the results of the respective measurements of the dosequantities of the impurities (boron) in the respective siliconsubstrates 13 containing different integrated deposition filmthicknesses of the boron radicals 21, it was found that there was acorrelation between the integrated deposition film thickness and thedose quantity of the boron radicals 21. As the result, it was found thatthe boron taken in the silicon substrate 13 was not the impurity ions(B_(x)H_(y) ⁺) in the plasma that were accelerated by the bias potentialand injected as they were, but that the boron was the boron radicals 21that were deposited on the surface of the silicon substrate 13 and werepushed in by the argon ions 22. Consequently, the impurity dose quantityin the silicon substrate 13 can be controlled by adjusting theintegrated deposition film thickness of the boron radicals 21 (that is,doping processing time).

Moreover, when the distributions of the impurities in the depthdirection were measured at the time of changing the bias RF power (i.e.the radiation energy of argon ions) with the integrated deposition filmthicknesses of the boron radicals 21 (i.e. doping processing times)fixed, it was found that there was a correlation between the bias RFpower and the distribution of the impurities in the depth direction.That is, it was found that, the higher the bias RF power was, the deeperthe position of the distribution of the impurities reached. Accordingly,the distribution of the impurities in the depth direction of the siliconsubstrate 13 can be controlled by adjusting the radiation energy of theargon ions 22.

Consequently, according to the present embodiment, because the controlof the dose quantity of impurities and the control of the distributionof the impurities in the depth direction can separately andindependently be performed, condition setting at the time of applyingthe present embodiment to the manufacturing process of a semiconductordevice becomes easy.

Moreover, it was found that the in-plane distribution of the sheetresistance value of the silicon substrate 13 could be controlled within1% by controlling the in-plane distribution of the deposition filmthickness of the boron radicals 32 on the surface of the siliconsubstrate 13 to be within 3% by the standard deviation σ/average value.Here, the in-plane distribution of the deposition film thickness of theboron radicals 21 on the surface of the silicon substrate 13 isinfluenced by the distribution of the boron radicals 21 in the plasma.Accordingly, it is appropriate to set the aforesaid magnetic field coilcurrents (upper and lower/intermediate) in such a way that thedistribution of the boron radicals 21 in the plasma becomes uniform.

Next, with reference to FIGS. 10 to 12, a manufacturing method of asemiconductor device of a fourth embodiment, to which the aforesaidplasma doping method of the third embodiment is applied, will bedescribed by illustrating a manufacturing method of a MISFET.

First, as shown in FIG. 10(A), the gate insulation film 32 is formed onthe silicon substrate 31. As the gate insulation film 32, for example, ahigh dielectric constant film (high-k film), such as a HfO_(x) film, aHfSiO_(x) film, and a HfAlO_(x) film, all having a film thickness offrom 2 nm to 3 nm, or a laminated film of the above-mentioned films canbe used in addition to a silicon oxide film and a silicon oxynitridefilm, both having a film thickness of from 0.5 nm to 1 nm.

In addition, the silicon oxide film can be formed by using the thermaloxidization method, and the high dielectric constant film can be formedby using the ALD (atomic layer deposition) method and the MOCVD (metalorganic chemical vapor deposition) method.

Next, a polysilicon film having a film thickness of from 70 nm to 100 nmis formed on the gate insulation film 32 by the LPCVD (low pressurechemical vapor deposition) method as the gate electrode film 33 to bethe gate electrode 33 a. In addition, the materials of the gateelectrode film 33 are not limited to the polysilicon, but silicongermanium, a publicly known metal, and the like can be used.

Next, impurities are introduced in the polysilicon film 33 by using theplasma doping method of the aforesaid third embodiment. That is, asshown in FIG. 10(B), the boron radicals 21 are pushed in the polysiliconfilm 33 by the argon ions 22 while depositing the boron radicals 21 onthe surface of the polysilicon film 33. At this time, by applying theaforesaid deposition conditions, the depositing speed of the boronradicals 21 and the etching speed of the boron radicals 21 by the argonions 22 are made to be equal to each other. In addition, a part of theboron radicals 21 a is not pushed in the polysilicon film 33, but isscattered.

In addition, it is appropriate to adjust the doping time, determiningthe integrated deposition film thickness of the boron radicals 21,according to the target dose quantity of boron (e.g. 5×10¹⁵ [cm⁻²]), andfor example, it is appropriate to set the doping time within a range offrom 20 sec to 40 sec. Moreover, it is appropriate to adjust the bias RFpower, determining the radiation energy of the argon ions 22, accordingto the target depth distribution of boron (for example, 1×10¹⁷ [cm⁻³] orless at the depth of 50 nm to 60 nm from the surface of the polysiliconfilm 33). That is, it is appropriate to determine the bias RF power lestthe impurities introduced in the polysilicon film 33 should reach thegate insulation film 32.

Then, a not-shown resist pattern is formed on the polysilicon film 33 byusing the lithography technique, and the polysilicon film 33 and thegate insulation film 32 are etched with the resist pattern used as amask. Furthermore, for example, after the resist pattern is removed bysuitably performing ashing processing and SPM (sulfuric hydrogenperoxide mixture) processing, thermal processing for activating theboron introduced in the polysilicon film 33 is performed in the publiclyknown lamp annealing apparatus. Hereby, as shown in FIG. 11(A), astructure in which the gate insulation film 32 and the gate electrode 33a, composed of a polysilicon film in which boron is introduced, arelaminated is formed. Next, an extension region is formed in the siliconsubstrate 31 by introducing impurities into the silicon substrate 31 byusing the plasma doping method of the aforesaid third embodiment. Thatis, as shown in FIG. 11(B), while the boron radicals 21 are deposited onthe surface of the silicon substrate 31, the deposited boron radicals 21are pushed into the silicon substrate 31 by the argon ions 22. Similarlyto the aforesaid introduction of the impurities into the polysiliconfilm 33, a part of the boron radicals 21 a is not pushed into thesilicon substrate 31, but is scattered. At this time, by applying theaforesaid doping conditions, the deposition speed of the boron radicals21 and the etching speed of the boron radicals 21 are made to be equalto each other.

In addition, it is appropriate to adjust the doping time, determiningthe integrated deposition film thickness of the boron radicals 21,according to the target dose quantity (for example, 1×10¹⁵ [cm⁻²]) ofboron, and it is appropriate to set the doping time, for example, withina range of from 20 sec to 40 sec. Moreover, it is appropriate to adjustthe bias RF power, determining the radiation energy of the argon ions22, according to the target depth distribution of boron (e.g. 5×10¹⁸[cm⁻³] or less at the depth of 10 nm to 15 nm from the surface of thesilicon substrate 31).

Then, thermal processing for activating the boron introduced in thesilicon substrate 31 is performed in the publicly known lamp annealingapparatus. Hereby, as shown in FIG. 11(C), the p-type extension region34 having a depth of 10 nm or less is formed in such a manner that thegate electrode 33 a lies between the extension regions 34.

Next, after forming a silicon oxide film on the whole surface of thesilicon substrate 31, the silicon oxide film is etched, and thereby, asshown in FIG. 12(A), the spacer 35 covering the side wall of the gateelectrode 33 a is formed by a self-aligned manner.

Then, as shown in FIG. 12(B), the boron ions 36 are injected into thesilicon substrate 31 with the gate electrode 33 a and the spacer 35 usedas masks by the ion implantation method. Furthermore, by activating theinjected boron ions 36 by thermal processing, source/drain regions 37deeper than the extension region 34 are formed as shown in FIG. 12(C). AMISFET can be obtained through the aforesaid steps.

In the fourth embodiment described above, while depositing the boronradicals 21 on the surface of the silicon substrate 31, the depositedboron radicals 21 are pushed into the silicon substrate 31 by the argonions 22 at the time of forming the extension region 34 after theformation of the gate electrode 33 a. At this time, the deposition speedof the boron radicals 21 and the etching speed of the boron radicals 21by the argon ions 22 are made to be equal to each other, and thereby thesurface of the silicon substrate 31 is covered by the boron radicals 21.Consequently, the surface of the silicon substrate 31 can be preventedfrom being etched by the argon ions 22. Consequently, the rise of thesheet resistance value of the silicon substrate 31 can be prevented, andthe lower resistance p-type extension region 34 can be formed.

Furthermore, in the present embodiment, similarly to the aforesaidextension region 34, the deposition speed of the boron radicals 21 andthe etching speed of the boron radicals 21 are made to be equal to eachother at the time of introducing the impurities into the polysiliconfilm 33, which is a gate electrode film. Hereby, the surface of thepolysilicon film 33 is covered by the boron radicals 21, andconsequently the surface of the polysilicon film 33 can be preventedfrom being etched by the argon ions 22. Consequently, the rise of thesheet resistance value of the polysilicon film 33 can be prevented.

In addition, the present invention is not limited to the aforesaidembodiments, but the present invention can be variously modified to becarried out within a scope of the spirit of the present invention.

For example, a boron trifluoride (BF₃) gas may be used in place of thediborane gas used at the time of the deposition of boron radicals.Moreover, other rare gases (such as helium) may be used in place of theargon gas.

Moreover, the plasma of a rare gas may be generated before thedeposition of the boron radicals, and rare gas ions (such as argon ions)in the plasma may be radiated onto the surface of the silicon substrate13 or the surface of the polysilicon film 33. Because the surface ishereby made to be amorphous, the excessive diffusion of the borane,introduced in the inside of the silicon substrate 13 or the polysiliconfilm 33, by the thermal processing of a post-process is suppressed.

Moreover, although the case of introducing boron, which is a p-typeimpurity, has been described in the aforesaid embodiments, the presentinvention can also be applied to the introduction of phosphorus orarsenic, which is an n-type impurity. In this case, it is appropriate tosupply a phosphine (PH₃) gas or an arsine (AsH₃) gas in place of thediborane gas.

Moreover, the argon gas is not needed to be supplied at the time of thedeposition of the boron radicals, and the diborane gas may be suppliedat the time of the radiation of the argon ions. Moreover, the depositionof the boron radicals and the radiation of the argon ions may beperformed in different vacuum chambers.

Moreover, although the case of introducing the impurities into thesubstrate or the film by using the ICP type apparatus has been describedin the aforesaid embodiments, the apparatus for introducing theimpurities is not limited to the ICP type one. For example, a parallelplate type apparatus may be used.

Moreover, it is also possible not to radiate the argon ions in plasma tothe surface of a substrate, but to lead the argon ions generated by apublicly known ion generation mechanism to the surface of the substrateto radiate the argon ions thereon, and to push boron radicals into thesubstrate or the film.

DESCRIPTION OF REFERENCE NUMERALS AND CHARACTERS

-   1 vacuum chamber-   13 silicon substrate-   15 high-frequency power source-   21 boron radical-   22 argon ion-   23 impurity diffusion layer-   31 silicon substrate-   32 gate insulation film-   33 gate electrode film-   33 a gate electrode-   34 extension region-   35 spacer-   37 source/drain regions

1. A plasma doping method of introducing impurities into an inside of anobject to be processed, comprising: a first step of generating plasma ofa gas containing the impurities to deposit radicals of the impurities inthe plasma on a surface of an object to be processed; and a second stepof radiating ions to the radicals deposited on the surface of the objectto be processed at the first step.
 2. The plasma doping method accordingto claim 1, wherein a time until the radicals deposited at the firststep do not exist on the surface of the object to be processed is setbased on an etching rate of the radicals etched by the ions radiated atthe second step, and the second step is performed for the set time. 3.The plasma doping method according to claim 1, wherein, when the firstand the second steps are executed in a same processing chamber, theplasma of the gas containing the impurities is generated and no biaspotential is applied to a substrate at the first step, and supply of thegas containing the impurities is stopped and the bias potential isapplied to the substrate at the second step.
 4. A plasma doping methodof generating plasma of a gas containing impurities and of introducingradicals of the impurities in the plasma into an inside of an object tobe processed by means of ions while depositing the radicals on a surfaceof the object to be processed, wherein a depositing speed of theradicals to the surface of the object to be processed and an etchingspeed of the radicals etched by the ions are made to be equal to eachother.
 5. The plasma doping method according to claim 1, wherein a dosequantity of the impurities introduced into the inside of the object tobe processed is controlled by adjusting a deposition quantity of theradicals deposited on the surface of the object to be processed.
 6. Theplasma doping method according to claim 1, wherein a distribution of theimpurities in a depth direction, the impurities introduced into theinside of the object to be processed, by adjusting radiation energy ofthe ions.
 7. The plasma doping method according to claim 1, wherein theions are radiated to the surface of the object to be processed beforethe radicals are deposited on the surface of the object to be processed.8. The plasma doping method according to claim 1, wherein the ions areones of a rare gas.
 9. A manufacturing method of a semiconductor device,comprising: a step of forming a gate insulation film on a surface of asubstrate; a step of forming a gate electrode on the gate insulationfilm; step of forming an extension region with the gate electrode usedas a mask; a step of forming a spacer covering a side wall of the gateelectrode; and a step of forming source/drain regions by using the gateelectrode and the spacer as masks, wherein the step of forming theextension region includes: a first step of generating plasma containingimpurities to deposit radicals of the impurities in the plasma on thesurface of the substrate; and a second step of radiating ions to theradicals deposited on the surface of the substrate at the first step.10. The manufacturing method of a semiconductor device according toclaim 9, wherein the step of forming the gate electrode includes: a stepof forming a gate electrode film to become the gate electrode; a step ofintroducing the impurities into the gate electrode film; and a step ofpatterning the gate electrode film in which the impurities areintroduced, and wherein the step of introducing the impurities into thegate electrode film includes: a first sub-step of generating the plasmaof the gas containing the impurities to deposit the radicals of theimpurities in the plasma on a surface of the gate electrode film; and asecond sub-step of radiating the ions to the radicals deposited on thesurface of the gate electrode film at the first sub-step.
 11. Amanufacturing method of a semiconductor device, comprising: a step offorming a gate insulation film on a surface of a substrate; a step offorming a gate electrode on the gate insulation film; a step of formingan extension region by using the gate electrode as a mask; a step offorming a spacer covering a side wall of the gate electrode; and a stepof forming source/drain regions with the gate electrode and the spacerused as masks, wherein the step of forming the extension region is thatof generating plasma of a gas containing impurities to introduceradicals of the impurities in the plasma into an inside of the substrateby means of ions while depositing the radicals on the surface of thesubstrate, and wherein a depositing speed of the radicals on the surfaceof the substrate and an etching speed of the radicals etched by the ionsare made to be equal to each other.
 12. The manufacturing method of asemiconductor device according to claim 11, wherein the step of formingthe gate electrode includes a sub-step of forming a gate electrode filmto become the gate electrode, a sub-step of introducing the impuritiesinto the gate electrode film, and a sub-step of patterning the gateelectrode film in which the impurities are introduced, and wherein thesub-step of introducing the impurities into the gate electrode film isthat of generating the plasma of the gas containing the impurities tointroduce the radicals of the impurities in the plasma into an inside ofthe gate electrode film by means of the ions while depositing theradicals on a surface of the gate electrode film, and a depositing speedof the radicals on the surface of the gate electrode film and an etchingspeed of the radicals etched by the ions are made to be equal to eachother.
 13. The manufacturing method of a semiconductor device accordingto claim 9, wherein the ions are those of a rare gas.
 14. The plasmadoping method according to claim 4, wherein a dose quantity of theimpurities introduced into the inside of the object to be processed iscontrolled by adjusting a deposition quantity of the radicals depositedon the surface of the object to be processed.
 15. The plasma dopingmethod according to claim 4, wherein a distribution of the impurities ina depth direction, the impurities introduced into the inside of theobject to be processed, by adjusting radiation energy of the ions. 16.The plasma doping method according to claim 4, wherein the ions areradiated to the surface of the object to be processed before theradicals are deposited on the surface of the object to be processed. 17.The plasma doping method according to claim 4, wherein the ions are onesof a rare gas.
 18. The manufacturing method of a semiconductor deviceaccording to claim 11, wherein the ions are those of a rare gas.